Coolant injection system for gas turbines



Aug. 17, 1954 D. J. J'CRDAN COOLANT INJECTION SYSTEM FOR GAS TURBINES 2 Sheets-Sheet 1 Filed May 8, 1948 INVENTOR.

.BY Dafiahi Joy-din.

ATTORNEY 1954 D. J. JORDAN COOLANT INJECTION SYSTEM FOR GAS TURBINES 1N VEN TOR.

2 Sheets-Sheet 2 BY Donald J. \fzmfan.

Filed May 8, 1948 A T TORNEY Patented Aug. 17, 1954 UNITED STATES PTENT OFFICE COOLANT INJECTION SYSTEM FOR GAS TUR-BINES Application May 8, 1948, Serial No. 25,955

6 Claims. (Cl. 230-209) This invention relates to improvements in coolant injection systems for gas turbine engines. More specifically this invention relates to an. improved mechanism for injecting a coolant liquid into the compressor intake of gas turbine power plants adaptable for use in aircraft to improve their efiiciency and power output.

It is an object of this invention to provide an improved coolant injection system for compressors of gas turbine power plants.

t is a further object of this invention to provide a system for injecting a liquid coolant into a compressor of a gas turbine power plant to reduce the back-work ratio of the turbine cycle.

Another feature of this invention resides in the provision of improved means for injecting liquid coolant into the compressor of a gas turbine power plant to produce results similar to that obtained by use of an inter cooler, thereby increasing the efficiency of the compressor and the over-all eiiiciency of the turbine cycle.

A further feature of this invention resides in the provision for a coolant injection system for gas turbine power plants particularly adaptable for use with aircraft power plant installations.

These and other objects will become readily apparent from the following detailed description of the accompanying drawings which illustrate one embodiment of the invention.

In these drawings:

Fig. 1 is a partial cross sectional view of a gas turbine engine including a schematic view of the water injection system;

Fig. 2 is a perspective view of the turbine casing showing the arrangement of the coolant injection nozzles and external collar;

Fig. 3 is an enlarged perspective cross sectional view of the casing shown in Fig. 2 including a detailed perspective of the nozzle; and

Fig. 4 is an enlarged partial cross sectional view of the fitting attachment through which the coolant is injected into the fluid-air injection casmg.

It is a well-known, major characteristic of gas turbine power plants that a great deal of power is expended to operate the compressor and accessories during the normal cycle. This work which is put back into the power plant is often referred to as the "back-work ratio. The backwork ratio as here used is the ratio of the total mechanical work which is absorbed by compressors and other equipment necessary to the operation of the cycle divided by the total work generated by the turbines or other prime movers in the cycle.

For example, a typical gas turbine cycle may have a back-work ratio of as high as two-thirds. Accordingly, in such a case, two out of every three H. P. developed is used to drive compressors or is otherwise absorbed in the cycle to give a net output of one H. P. As a result, any inefficiency in either the power generating or the power absorption equipment rapidly cuts down the net output. A logical method for increasing the net output would be to in rease the efficiency of the compressor. One obvious way would be to intercool the compressor at one or more stages. However, this is often mechanically difficult and inefficient.

An eifect similar to intercooling can be ob tained without actually removing heat from the cycle by injecting a mixture of air and finely divided liquid such as water in the intake of the compressor. In this way the heat of compression of the air is absorbed as latent heat in the water which is evaporated. This process, often referred to as wet compression, reduces the work done by the compressor in much the same way as intercooling does. However, the net result is a reduction in work of compression and an increase in the total volume of compressed working fluid which is delivered by the compre sor. This in turn reduces the back-work ratio and increases the net power output from the entire cycle.

Referring to Fig. 1, a typical aircraft gas turbine jet power plant is generally indicated at If]. The power plant is comprised of an outer casing l2 forming an intake duct ii and housing an axial flow compressor iii, a combustion chamher or generator i8 and a turbine Zii. Air is normally ducted through the intake it, through the compressor 55, then into the compressor outlet chamber 22, and through the combustion chamber 18. The gases from the combustion chamber enter the turbine 2:. and are emitted through the jet exhaust chamber 24.

According to this invention a coolant injection system is provided for the power plant by forcing a liquid under pressure through a nozzle where it is mixed with compressed air to provide atomi zation and thereafter injected in the intake 14 of the compressor. For this purpose one or more holes 39 are provided in the periphery of the power plant casing 52 at the compressor outlet. The compressed air passes through the conduit 32 to the T-fitting er. One leg of the i'- fitting leads to the conduit it through the check valve 38 to provide a pressure within the liquid coolant tank 49. The other leg of the T-fitting 34 leads through the conduit 42, through a shutoff valve 44 and thence to an annular collar 50 V on the cylindrical coolant injection assembly 52. A pipe 55 terminates beneath the liquid in the coolant tank 49 which permits the passage of liquid under pressure through the shut-oil valve to points of attachment on the collar 56. The pipe arrangement illustrated in Fig. 1 has been shown for the sake of simplicity. This arrangement can be modified in aircraft installations according to various well-known practices to insure constant liquid supply in all attitudes of flight.

As is better shown in Figs. 2 and 8, the coolant injection assembly 52 has radially extending mounting flanges Eel for attaching it to the power plant, casing l2. A series of nozzles are mounted circuinferentially in the assembly In order to provide separate chambers by which the liquid coolant and the compressed air can be supplied to the nozzles for mixing, a separable annular collar 56 is provided. The inner por tion of this collar is formed by a U-shaped ring 5?: which is rigidly attached to outer face of the surface 62 of the coolant injection assembly 52 thereby defining the inner chamber lid of the collar as. The outer chamber 3 2 of the collar 55 is formed by attaching a ring 85 or" semicircular cross section to the ring til by means of loci: rings or lock cables 55. An airtight rubber seal it is provided bet een the mating surfaces of the ring 69 and he ring 65.

As s'tatedahove, the nozzles 55 are mounted at spaced intervals around the assembly 52 directly beneath the rings 6% and 55 which comprise the collar Each of the nozzles has a hollow core Bil which is threaded into a drilled passage in the ring so and held in position by a nut $2. The external threads on the core as extend upwardly above the lower surface of the ring iil'i to permit the nozzle cap 84 to be attached thereto. The upper surface of the cap is flush with the inner face of the surface 62 of the assembly When assembled, the upper portion or" the core of the nozzle is somewhat smaller than the H the annular chamber as therebetween.

One or more ports or a e provided in the side wall of the cap 8% to permit liquid to pass from the chamber es inside the ring he through the chamber The nozzle core to contains a central opening with a Venturi throat for permitting the passage of air from within the chamber es of the ring 55 through the open top 95 of the nozzle. air passes through the throat he its velocity is thereby increased, following which it mixes with the liquid passing through the open top of the nozzle from the chamber as to produce an atomized spray. One or more connections lie are provided in the ring 52 to permit the coolant liquid to forced into the cham ber 63 from the tank. lfi. Similar connections H32 are provided in the ring 65, to permit compressed air to enter the chamber ti from the conduit and'valve is. The connections Hi l and :52 are preferably welded to the walls of their respective chambers. the fitting l to is shown in Fig. i.

Thus it can be seen that when additional power is to'be derived from the power plant, the valves M and 5? are opened. Compressed air from the compressor outlet chamber 22 will pass through the conduits 32 and 3S to'force liquid from the tank 4% through the valve 5?, through the connection H6 into the chamber 63 of ring 60. The

=e diameter of the cap 84 thereby forming A typical installation for ports 92 permit the liquid to pass within the nozzle chamber 96 and then upwardly to the open top of the nozzle. At the same time, compressed air also passes through the valve 44, through the connection H2 and into the chamber 6d of ring 85. From here it flows through the throat 94 of the core so where it mixes with the liquid coming from passage as to provide the desired atomization. Preferably, the air valve 54 is opened first to insure atomizationwhen the liquid reaches the nozzles.

The core to of the nozzles can be properly adjusted by raising or lowering it along its threaded connection to increase or decrease the size of the chamber '38 in the vicinity of the opening 95. The nozzle core may also be varied in design according to the liquid-air ratio desired or ac cording to the spray pattern necessary.

It should be pointed out that the coolant liquid is preferably composed of a mixture of pure or distilled water and alcohol. It is important that a distilled water or a pure liquid is used since any impurities .izesent will precipi te during vaporization in'the compressor. The alcohol obviously to prevent icing.

As a result of this invention it is apparent that a mechanism has been provided for continuously or intermittently injecting a coolant liquid into a turbine engine thereby increasing its overall efiiciency.

In addition a mechanism has been provided for injecting a liquid coolant into the compressor of a gas turbin power plant to increase the compresscr efficiency and reduce the baclowork ratio of the turbine power plant thereby increasing the total output and thermal efficiency of the turbine cycle.

This invention also provides a means for increasing the mass delivered by the compressor of a turbine to increase the total power output or the power plant. The mechanism providing the foregoing advantages almost completely devoid of moving parts thereby making it particularly useful in aircraft where reliability is of primary importance.

Although only one embodiment of the invention has been disclosed in the accompanying .description of the drawings it will be evident that various modifications can lie-made without departing from the scope of this novel concept.

' claim: 7

1. In a turbine power plant, a compressor having a discharge passage and mechanism for injecting a liquid coolant into compressor including a coolant supply, an intake casing on said compressor, a plurality of mixing nozzles on the periphery of said casing forming passages there through, an am collar enclosing said nozzles having inner and outer concentric chem; rs each communicating with nozzles, a connection between said coolant supply and one of charnbers for supplying coolant thereto, connection between said discharge passage and the oth r of said chambers for supplying compressed air thereto, and a connection between discharge passage said coolant supply for pressurizing the same.

2. In an axial flow turbo-jet power plant a compressor, an air inlet for compressor, a discharge'passage from said compressor, means for increasing the mass of the air passing through a said compressor while maintaining a constant volume rate of air flow through the latter comprising mechanism for injecting a coolant liquid into said compressor, said mechanism including a coolant supply, a first annular chamber surrounding said compressor inlet, a second annular chamber in juxtaposition to said first mentioned chamber, a connection between said first mentioned chamber and said coolant supply, a con nection between said discharge passage of said compressor and. said second mentioned chamber for supplying compressed air thereto, a connection between said discharge passage and said coolant supply for pressurizing the same, and means for introducing atomized coolant into said air stream passing through said inlet at spaced points about the periphery of said inlet including a series of nozzles, each nozzle having concentric passages communicating respectively with said first and said second chambers.

3. In an axial flow turbo-jet power plant having a casing, a compressor within said casing, an air inlet through an open end of said casing to said compressor, an outlet passage within said casing from said compressor, a plurality of injection nozzles in said casing adjacent said air inlet, a liquid supply externally of said casing, a hollow collar concentric with said casing and attached thereto and communicating with said injection nozzles, communicating means between said liquid supply and said collar, said conduit means from the outlet passage of said compressor to said liquid supply to force said liquid to said nozzles through said collar.

4. In an axial fiow turbo-jet power plant having a casing, a multiple stage compressor within said casing, an air inlet through an open end of said casing before the first stage of said oompressor, a discharge passage within said casing after the last stage of said compressor, a liquid coolant supply externally of said casing, a plurality of injection nozzles in said casing adjacent said air inlet for injecting said coolant into said air inlet before the first stage of said compressor, a first chamber attached to said casing and communicating with said nozzles and with said liquid coolant supply, a second chamber attached to said casing adjacent said first chamber attached to said casing and communicating with said nozzles and with said liquid coolant supply, a second chamber attached to said casing adjacent said first chamber, a conduit from said discharge passage to said second chamber for directing high pressure air thereto, and means for atomizing said liquid coolant in said nozzles including communicating means from said second chamber to said nozzles.

5. In an axial flow turbo-jet power plant having a casing, a multiple stage compressor within said casing, an air inlet through said casing to the first stage of said compressor, a discharge passage within said casing after the last stage of said compressor, a liquid coolant supply, an injection nozzle in said casing adjacent said air inlet for injecting said coolant into the air admitted to said compressor, a first chamber for the accumulation of said coolant communicating with said nozzle, communicating means between said coolant supply and said first chamber, a second chamber for the accumulation of high pressure air communicating with said nozzle for atomizing said coolant in said nozzle, a first conduit from said discharge passage to said coolant supply for forcing said coolant to said first chamher, and a second conduit from said discharge passage to said second chamber for providing high pressure air thereto.

6. In an axial fiow turbo-jet engine having a casing, a multiple stage compressor within said casing, an air inlet to the first stage of said compressor through said casing, a plurality of injecticn nozzles in said casing for admitting coolant to the air admitted to said compressor, a discharge passage within said casing after the last stage or" said compressor, a liquid coolant supply, a first hollow annular collar concentric with said casing for providing a chamber adjacent said nozzles and communicating therewith, communicating means between said coolant supply and said first collar for the passage of liquid coolant, a second hollow annular collar concentric with said casing for providing a second chamber communicating with said. nozzles, a first conduit from said discharge passage to said liquid coolant supply for forcing the same to said first collar, and a second conduit from said discharge passage to said second collar for supplying high pressure air to said nozzle for atomizing said coolant as it passes through said nozzle.

References Cited in the file of this patent UNITED STATES PATENTS- Number Name Date 1,400,813 Graemiger Dec. 20, 1921 1,824,893 I-Iolzwarth Sept. 29, 1931 2,433,998 Halford Apr. 6, 1948 FOREIGN PATENTS Number Country Date 3,607 Great Britain Feb. 21, 1905 111,381 Great Britain Nov. 29, 1917 372,377 Great Britain May 4, 1932 745,590 France Feb. 21, 1933 

